The field of the invention is internal combustion engines and the invention relates more particularly to tools for determining the optimum length for each push rod in a push-rod engine.
It is important to have push rods of the correct length because engines run better and exhibit less wear when the push rods are the correct length. The valve timing is more precise, the loading on the push rod is less and wear is reduced. Furthermore, the engine will turn a higher RPM and will produce more power as a result of less friction and more precise valve timing.
Engines that have been modified with higher lift cams are much more critical to push rod length and thus, after installing a high lift cam, the optimum push rod length should be determined. In addition to changing cam shafts, adding or removing of gaskets or changing the deck height on the cylinder head also requires a push rod length adjustment. The goal is to have a 90.degree. angle between the rocker arm shaft, center of the push rod ball, and the axis of the push rod, measured at one-half the valve lift.
In the past, it has been very difficult to measure ideal push rod length, and thus, a trial and error method has typically been used which leads to less than perfect results.